DEDUCTIONS FROM SOME FIELD ARTILLERY PRACTICE. 51 7 
The first eleven 
figures again. 
figure shows the effect at \2]/ 2 % to that at 0% misobserved to be as 6 
to 9.5. That is with 12^% misobserved there is a loss in effect of 
37% ! (12 }4% were actually misobserved). 
The figure has been drawn from 40 series of 38 rounds of which 7 
were ranging rounds. Average range about 2400 yards. Stations 
various. Range measured with a mean error of + 70 yards. Target, 
infantry in fours. The curve is very doubtful towards 40% and 50%. 
In the 42 series, Figs. I. to XI., the probable fuze 
error due to weather and various “ thousands ” was 
almost exactly According to this, the correct 
fuze may possibly vary 10% ; thus the great importance of having 
fuzes of one number of thousand and knowing them well, or of having 
a mechanical fuze, is easily realised. The necessity of noting the 
weather and the information on the fuze-tin’s lid is also clear. Even 
with a mechanical fuze some error will remain. 
The curves That the changes of each effect-curve as it passed 
generally and through or neared the maximum or minimum should 
misobservation be slow was expected, but that they should be as slow 
in particular. as the curves disclose came to me as a surprise. 
Yet the fact is easily accounted for. When we consider theore¬ 
tically the effect for instance of bad fuze setting we are apt 
to leave the other errors out of account, but all errors come into 
play when we actually shoot. Thus all the curves get flatter or spread 
themselves out further than we might at first suppose.Each error is 
bad, but none is quite as black as sometimes painted. Misobservation 
is by far the worst. It is so serious that it seems desirable that the 
observer should be a specially paid and trained specialist, whose only 
duty in action was observation and who could use a telescope as well 
as a naval signalman can. Von Rohne’s estimate of misobservation is 
10%. That amount would appear to result in a loss in hits of about 
30% ! I have too few practice reports of the last few years to enable 
me to fix the English percentage now misobserved. But, if it reaches 
Von Rohne’s estimate, the advent of specialist observers is as sure as 
that of Christmas. 
My analyses show misobservation to be only about 7%, but most of 
the practice took place under easy conditions. 
